Inconsistent physics when changing localscale

I noticed an inconsistent jump height when flipping my character's orientation mid air, so i made a test scene.

They're simple sprites that get launched by setting their velocity once, one of the sphere gets flipped twice, the other 20 times, the more they flip the less height they get, why does changing localscale.x affect physics, and what can be done about it?

Attached Files:

I tried removing the flipping part from the script, and make a separate script just for the flip, and add the script to the child which flips the parent, and the same thing happens, unless i misunderstood your explanation?

Edit: I'm taking a look at your project and i see what you mean, however I'm not sure why my version isn't working as I pretty much did the same thing, I'll keep messing around and maybe submit a bug report

I haven't tested 2018.2 yet, you can test the scene that I attached in the previous post and check if the spheres are synchronized or not, if they are not someone should make a bug report, I'll update soon but right now i'm a bit busy